This invention is generally concerned with gaseous flow control in and around an apparatus which provides heat through controlled combustion. More specifically, it concerns automatic and thermally-responsive control valves and check valves for gaseous passages in a wood-burning stove. Additional features concern a fixed-shield baffle system around a combustor of a wood-burning stove. The baffle system generally provides a more balanced flow of a mixture of combustion gasses and fresh air across the surface of the combustor.
In general, conventional wood-burning stoves have various openings and/or passageways which permit fresh air to flow from outside of the stove into an interior firebox. Also, it is known to provide a flow of combustion gas materials through a combustor operative with a wood-burning stove. Such a combustor may be associated with a heat exchanger having its own flow of air and having heat dissipation fins disposed therein. It is generally known to control both the flow of air into the firebox ("primary" air flow) and the flow of ("secondary" air flow) and combustion gasses to the combustor so as to respectively control both the firebox combustion operation and combustion function of a conventional wood-burning stove.
During desired operation of a conventional wood-burning stove, smoke and other gaseous by-products of combustion are exhausted up through a flue and out a chimney. It is generally known that, due to pressure changes or other unintended flows of air, some smoke or gaseous combustion by-products may back up in the firebox and be exhaused into a room through an intake air passage. Such a highly undesirable and potentially dangerous event is commonly referred to as "back puff."
One of ordinary skill in the art understands that controlling the amount of intake air into a stove influences the level of combustion activity within the stove. Accordingly, it is generally known to automatically control intake air paths with thermally-responsive control valves. Such conventional control valves have the goal of automatically controlling the stove combustion operation. However, such control valves in general do not readily accomodate other features in a single, integral device. For example, in general a single conventional control valve does not also provide protection against the problem of back puffing, discussed above.
Further, conventional wood-burning stoves may be equipped with a combustor element, which is typically a solid cylinder comprised of porous material. Gaseous materials from the firebox of a stove are passed through and around the combustor so as to fuel its operation. If the flow of combustion gasses in and around the combustor is not properly controlled so as to be relatively uniform in nature, the combustor element itself functions in an uneven pattern of varying temperatures.
Such operation causes problems in that the combustor may be physically damaged and its life significantly shortened by uneven operation. For example, if one peripheral area of the combustor is substantially hotter than remaining portions, the expansion of the hotter area will act as a wedge to split the combustor diagonally across its diameter. Alternatively, if the flow of combustion gasses in and around the combustor is such that the centermost portion of the combustor is hotter than the surrounding portions, the center will be crushed by its cooler and harder surroundings as it attempts to expand. When this occurs, the center of the combustor will simply become separated from the remainder of the combustor and fall out of the combustor. In either instance, the combustor must be replaced, which can be both expensive and time consuming.